In recent years, advertisement, propaganda and news contents have been expressed on a display panel with numerals, letters or symbols so as to deliver intended means to users. Such a display panel may be constructed of monochrome or color LEDs (Light Emitting Diodes) uniformly arranged thereon to display an advertisement image in monochrome or full color.
FIG. 1 shows a typical display apparatus for advertisement which displays advertisement having various kinds of numerals, letters or symbols. As shown in FIG. 1, the display apparatus includes a display panel 10 having a number of LEDs 11 uniformly arranged on a front side thereof; a case 30 to support the display panel 10; a sun screen 20 of lattice type coupled with a dielectric resin on the front surface of the case 30 to prevent light from being projected on the LEDs 11; and a driver 40 disposed in the back of the case 30 to control operations of the LEDs 11.
In the display apparatus as described above, advertisement are produced on the LEDs, for example, in a form of an image, and the advertisement image, in most cases, have a limited number of fixed frames, i.e., a single or a few frames. Accordingly, since the advertisement image having at most a single or a few frames are represented on the display panel 10, a viewer feels monotonous to see the advertisement image, thereby decreasing effectiveness of such advertisement. Further, the advertisement image produced in this manner does not permit a free editing so that it is not possible to make various changes to the advertisement image.
In addition, the display apparatus represents the advertisement image only linearly, which is one of many characteristics of LEDs. Since light from the LEDs 11 has a high linearity at an angle, as shown in FIG. 2, when viewing the display panel from a side, it is impossible to easily identify the advertisement image represented on the display panel 10.